Scientia Pro Publica 23: Biology

The oldest living tree (and organism?) might be Pando, an aspen root that's be shooting trees" for perhaps 80,000 years. It's also the heaviest living organism at over 6 million kilograms. Eric has more on The Earth's Oldest Trees:

The world's oldest trees are not necessarily trees as we think of them. They're not one trunk with branches and leaves that has stood for a million years. The oldest trees are actually clonal colonies, a series of genetically identical individuals deriving from one ancestor. With trees, that means a really old root colony that has continually produced shoots over millennia.

Like northern cardinals, domestic chickens are sexually dimorphic. So when Dr Clinton first saw these oddly lopsided chickens, he was immediately impressed by the birds' striking appearance: the larger male side had white feathers, spurs, large wattles and breast muscles, whereas the smaller female side showed the characteristic dark coloring, small wattles, and the lack of spurs (Figure 1).

If Darwin's work was already "social" and could be applied to politics with the ease that some authors have suggested, why did the editors of al-muqtataf need to emphasize the sociology of Spencer to pursue their political goals? The discussion of Darwin in this Arabic journal, at least as Elshakry presents it, emphasized his biological ideas and never made a connection between Darwin and the ideas of social Darwinism. While ideologues such as Weikart or Harun Yahya are unlikely to give up in their attempt to tar and feather Darwin with Spencer's philosophy, it's comforting to know that science enthusiasts in the Middle East knew the difference.

What Popeye the sailer man and fish at the bottom of the ocean have in common? Dr. M explains that they both eat spinach. For, the interesting observation here is that these fish are resource generalists, which implies something about evolutionary dynamics. Spinach, Popeye, and Fishy Pigeons. Journal article

Ahh, but what about spinach, you ask? Recent work by Jeffreys and colleagues indicates that macrouirds do indeed eat spinach. Baited traps with spinach placed on the deep-sea floor, quickly attracted fish and then spiraled into feeding frenzies (video at the BBC). But wait! You are asking yourself how often does a rattail actually encounter spinach or for that matter other leafy greens? Here in lies the genius. Spinach is just an easily obtainable surrogate for any land plant and the question is whether deep-sea fish are even equipped to detect a plant food fall. Apparently they can. This study indicates these dominating organisms of the deep can quickly utilize a variety of food sources in the deep; they are opportunistic.

Mike Fowler makes an argument that is I feel very strongly about. He has done population modeling, and his simulations are invariably quite simple compared to the real world. Some reviewers will argue that the simulations aren't close enough to reality, and therefore useless. However, throwing everything into the model makes it impossible to say which components are responsible for the observed effects, and therefore it is not just easier, but at times also imperative to keep the models simple, as Mike explains in Why I do what I do (and don't what I don't) Journal article

So why do I use the simple models? With competition models, you only have to worry about the distribution of competitive strengths (a single kind of interaction) among species. With natural enemy models, you will have to think about how interactions work across trophic levels, and might have to consider how competition works within trophic levels on top of that. There are more things to think about controlling and varying, making any results harder to investigate, think about and ultimately communicate. It's a bit reductionist, but I think it's worth understanding what happens in simpler models, to allow us clearer insight before we start dealing with the more complex models.

It is easy to make the assumption that bigger brains - meaning higher intelligence across species - implies high fitness, but big brains is not an advantage in all species, as Katie Kline explains in The phrenologist’s guide to ecological competence Journal article

They found that the migratory birds tended to have smaller brains than their resident relatives. While there likely are other contributing factors, the scientists propose that the longer migration routes led to the development of smaller brains—an ecological selection that possibly balances the costs of an energy-intensive flight.

Kelsey Abbott has a thing for critters with remarkable genitalia, so she couldn't possible not dissect this story about a beetle with a penis twice the length of it's body: Shouldering: Penis Extraction in Rove Beetles. Journal article

This unassuming poop-populating beetle has what scientists call “exaggerated genitalia.” When fully extended, the male’s flagellum (essentially a guiding rod for the sperm delivery system known as a spermatophore tube) is more than twice the length of the male beetle’s body. While impressive (and disturbing), living with such a long schlong isn’t nearly as glorious as it may sound.

(...)

He begins by slowly separating himself from his mate, exposing just a bit of the flagellum, keeping it under tension. He tucks the flagellum between his mesothorax and prothorax (parts of his shoulder) and then backs farther away from the female so that half of the flagellum is free. With the flagellum held taut in his shoulder, the male turns away from the female to extract the rest of the flagellum and then carefully coils it into the aedeagus (the holster for the flagellum and spermatophore tube). If he extracts and stores his equipment properly, he can mate up to five times in one hour. [Emphasis added.]

Using their new method, most eggshell samples from both ratites and from other Holocene birds yielded aDNA, indicating that avian eggshell can potentially preserve DNA for very long periods of time, even in hostile environments that have not traditionally been conducive to long-term DNA survival.

Microbial resistance to novel drugs is both an extremely important area of medical science, and one of the best examples of evolution caught in the act. As if dealing with microbes that can evolve resistance to one drug wasn't enough (it is), now bacteria can apparently also evolve resistance to other drugs. Jim Caryl describes A radical source of antibiotic resistance… Journal article

The aim was to determine whether treatment with one antibiotic could confer cross-resistance resistance to other antibiotics.

(...)

The researchers found that true enough, growth in one of the antibiotics – most notably ampicillin – resulted in cross-resistance to a number of the other antibiotics.

On the inside of each lobe are three or more tiny sensitive hairs. If an insect, spider or human finger touches more than one of these hairs—or the same hair more than once—in fewer than 30 seconds, the trap will snap. Interestingly, rain rarely triggers the traps because the likelihood of a raindrop falling in exactly the same place twice in under 30 seconds is negligible—a good thing for the Venus flytrap, who would otherwise starve every time it rained.

What could be more phascinating than a natural loo made of a plant? Phytophactor presents the (somewhat misnamed) giant pitcher plant and Real Crappy Plant Research

By positioning a nectar reward on its lid, small mammals like tree shrews are positioned such that when they defecate, the “results” end up in the pitcher. And when you think about it, this particular pitcher does sort of look like a toilet.

When stalking, the assassin bugs will rely on stealth to reach their prey undetected, severing and stretching the silk threads of the web between itself and the spider, and approaching it with an irregular, bouncing locomotion. Exploiting periods of environmental disturbance (caused by wind, for example), together with the vibrations created by its cryptic stepping movements, the assassin bug creates a kind of “smokescreen” effect to mask its approach.

When luring, however, the assassin bug will manipulate the silk vibrations to deliberately reveal its location on the web and draw the spider to it, plucking the threads to emulate the twitching, panicked movements of ensnared prey for up to twenty minutes. “The spider thinks it’s getting a meal, but instead gets eaten itself,” says Wignall.

Puerto Rican stray dogs, aka sato, aren't prized as much as pedigree dogs, but Bonn Aure thinks their bad reputation is undeserved; the distinction is artificial and based on aesthetics. Dog Days: The Sato in Punta. Journal article

A recent study by Gray et al (open access) also said that the small dog haplotype is derived from Middle Eastern gray wolves. They revealed that “all small dogs possess these diagnostic mutations, the mutations likely arose early in the history of domestic dogs.”

Ravens and crows are my favorite birds (unless velociraptor counts as one). I've seen crows chase off hummingbirds, stealing "their" nectar from coral tree flowers. But apparently they aren't as clever as I thought wished for. John describes a test that's too hard for some of them: Meat on a String: A Possible Limit to Corvid Intelligence? Journal article

It seems that researchers have found a limit to corvid intelligence. Even if they do not have the benefit of causal reasoning, crows and ravens still best other bird species at the string pulling problem. Some finches can complete a simple string-pulling task but have a much higher error rate, and many finches never figure out the solution. Even naïve crows, however, can solve the simple string problem almost immediately. Their larger forebrains may allow corvids to process and act on visual feedback more quickly than birds in other families.

Pleiotropy comes from the Greek πλείων pleion, meaning "more", and τρέπειν trepein, meaning "to turn, to convert". It designates the occurrence of a single gene affecting multiple traits, and is a hugely important concept in evolutionary biology.

I'm a postdoc at UC Santa Barbara.

All Many aspects of evolution interest me, but my research focus is currently on microbial evolution, adaptive radiation, speciation, fitness landscapes, epistasis, and the influence of genetic architecture on adaptation and speciation.